Mo. Rev. Stat. § 454.511

The division may certify a person who owes a child support arrearage in excess of the amount set forth in 42 U.S.C. 654(31) to the appropriate federal government agency for the purpose of denying a passport to such person, or revoking, suspending or limiting a passport previously issued to such person. Such person shall be mailed, by the division or on behalf of the division, a notice of the proposed certification and the consequences thereof upon such person. Within thirty days of receipt of the notice, the person may contest the proposed certification by requesting in writing a hearing pursuant to the procedures in section 454.475. At such hearing the obligor may assert only mistake of fact as a defense. For purposes of this section, "mistake of fact" means an error in the amount of arrearages or an error as to the identity of the obligor. The obligor shall have the burden of proof on such issues. The division shall not certify the person until after a final decision has been reached.